The United States community solar market is approaching a tipping point. In its latest report, U.S. Community Solar Outlook 2015-2020, GTM Research forecasts the market to grow fivefold this year with 115 megawatts installed. By 2020, community solar in the United States will be an annual half-gigawatt opportunity.

With 66 cumulative megawatts installed through the end of 2014, the U.S. community solar market is just getting off of the ground. However, GTM Research has pegged it as the most significant solar growth market for the United States. Between 2014 and 2020, GTM Research expects U.S. community solar to have a compound annual growth rate of 59 percent.

According to the report, there are 24 states with at least one community solar project on-line, and 20 states have or are in the process of enacting community solar legislation. However, only four states will install the majority of community solar over the next two years: California, Colorado, Massachusetts and Minnesota.

In the near term, these state markets with community solar legislation will serve as the core drivers of demand, fueling just over 80 percent of installations over the next two years.

“Looking ahead to 2020,” said Senior Solar Analyst Cory Honeyman, “the community solar opportunity is poised to become more geographically diversified, as developers ramp up service offerings to utilities in states without community solar legislation in place and national rooftop solar companies enter the community solar scene.”

The report identifies 29 developers that are actively working on community solar projects. Today two companies, Clean Energy Collective and SunShare, together account for 32 percent of operating community solar capacity.

However, GTM Research expects a wave of market entry and expansion over the next five years, as rooftop solar companies including NRG, SunEdison, and SolarCity build out their community solar efforts.

The next five years will see the U.S. community solar market add an impressive 1.8 gigawatts, compared to just 66 megawatts through the end of 2014